Charge control agent and toner for electrostatic image development

ABSTRACT

A charge control agent of the present invention comprises aggregate particles of an azo-type iron complex salt represented by the following chemical formula [I] 
                 
 
in the chemical formula [I], R 1 —, R 2 —, R 3 —, R 4 —, R 5 — and R 6 — are same or different to each other, n is 0.7 to 0.99, 
the aggregate particles have an average particle size of 1 to 4 microns and an average particle size of a primary particulate crystalline, that is fined the aggregate particles with ultrasonic irradiation, is at most 3 microns. A toner for developing an electrostatic image comprises a resin for the toner and the charge control agent.

BACKGROUND OF THE INVENTION

This invention relates to a negative charge control agent includingazo-type iron complexes which is used for a toner for an electrostaticimage development or a powder paint and the toner for an electrostaticimage development including the agent.

An electro photography system applied to a copy machine, printer orfacsimile performs to develop an electrostatic latent image onphotosensitive frame by toner having frictional electrification and theimaged toner to transfer and then fix onto a paper.

A charge control agent is added to the toner beforehand so as for thetoner to quicken a rise speed of the electrification, electrifysufficiently, control a proper quantity of the electrification stably,improve electrification property, rise up a speed for developing theelectrostatic latent image, and form the vivid images. For instance, asthe negative charge control agent, metallic complex salts are mentionedin Japanese Patent Provisional Publication No. 61-155464.

In recent year, a copy machine or printer causes high efficiency withimproving resolution and so on. The electro photography system is usedwith not only a high speed development but also a low speed developmentin widespread purposes. Therefore, it is required that the chargecontrol agent causes faster rise speed of the electrification of thetoner, more excellent electrification property, the agent is able toform the vivid images of high resolution, and the agent is able to bemanufactured simply. And it is required that the charge control agent isable to be used of a powder paint for a electrostatic powder printingmethod which attracts and bakes the powder paint onto a surface of aframe work having charge.

SUMMARY OF THE INVENTION

The present invention has been developed to solve the foregoingproblems.

It is an object of the present invention to provide the charge controlagent manufactured simply, and its manufacturing method. The chargecontrol agent causes the fast rise speed of the electrification,excellent electrification property, making to form the vivid images ofhigh resolution. It is another object of the present invention toprovide the toner for electrostatic image development including thisagent, and the images formation method used this toner.

The charge control agent of the present invention developed foraccomplishing the foregoing object, comprises aggregate particles of anazo-type iron complex salt represented by the following chemical formula[I]

in the chemical formula [I], R¹—, R²—, R³— and R⁴— are same or differentto each other, and one thereof is selected from the groups consisting ofa hydrogen atom, an alkyl group having a straight or branch chain of 1to 18 carbon atoms, an alkenyl group having a straight or branch chainof 2 to 18 carbon atoms, a sulfonamide group being to havesubstitutional groups, a mesyl group, a hydroxyl group, an alkoxyl groupof 1 to 18 carbon atoms, an acetylamino group, a benzoylamino group, ahalogen atom, a nitro group and an aryl group being to havesubstitutional groups; R⁵- is a hydrogen atom, an alkyl group having astraight or branch chain of 1 to 18 carbon atoms, a hydroxyl group or analkoxyl group of 1 to 18 carbon atoms; R⁶— is a hydrogen atom, an alkylgroup having a straight or branch chain of 1 to 18 carbon atoms, ahydroxyl group, a carboxyl group, a halogen atom or an alkoxyl group of1 to 18 carbon atoms; n is 0.7 to 0.99,

the aggregate particles have an average particle size of 1 to 4 micronsand an average particle size of a primary particulate crystalline, thatis fined the aggregate particles with ultrasonic irradiation, is at most3 microns.

Since the charge control agent is fine, it is unnecessary to grind usinga powerful pulverization equipment like a jet mill. When a toner forelectrostatic image development of the several micrometers particlesize, that is prepared by melt-kneading the charge control agent of fineaggregate particles within this range of average particle size and theresin for the toner, is magnified with a scanning electron microscope,it is observed that the charge control agent is dispersed homogeneouslyinto the particles of the toner. Consequently the toner, whose thecharge control agent is exposed sufficiently on the surface thereof,causes the equal and excellent electrification property. If the averageparticle size of the aggregate particles of the charge control agent ismore than 4 microns, the toner causes decreasing the dispersibility andelectrification property thereof. It is preferable that the chargecontrol agent comprises the aggregate particles whose average particlesize ranges from 1 to 3 microns.

It is preferable that a size of a primary particle of said azo-type ironcomplex salt represented by the above chemical formula [I] is at most 4microns.

It is guessed that the charge control agent of the aggregate particleshaving the average particle size of 1 to 4 microns are formed byassociation of several superfine primary particles. If the fined primaryparticles are larger than the above range, the average particle size ofthe charge control agent of the aggregate particles associated withequal number of the primary particles is more than 4 microns.

The toner for electrostatic image development prepared with the chargecontrol agent, that comprises the azo-type iron complex salt having thecounter ions of above ratio of the ammonium ion and the sodium ion,causes fast rise speed of the electrification under the high and lowspeed development of the electrostatic latent image. Further the tonercauses electrifying sufficient quantity of charge and keeping stableelectrification. If n is out of the above range, the toner causes alower rise speed of the electrification under the lower speeddevelopment of the electrostatic latent image, and the toner causeselectrifying insufficient quantity of charge.

A common main skeleton of the azo-type iron complex salt is representedby the following structural formula [IV]:

The skeleton has a central metal of an iron atom, and a metal-chelatingstructure with 2 molar equivalents of the monoazo compound and 1 molarequivalent of iron atom. The monoazo compound has a naphthalene ring. Ahydrogen atom of the naphthalene ring is substituted by an anilide grouprepresented by the following group [V]:

Each of the monoazo compounds having the naphthalene ring substituted bythe anilide group and the azo-type iron complex salt derived fromthereof improve oil insolubility.

It is difficult to prepare the azo-type iron complex salt by reason oftendency to react among solids. And the salt is difficult tocrystallize. Further the salt tends to disperse heterogeneously byreason of lowering of compatibility with the toner resin. For obtainingthe toner having excellent charge controlling property and welldeveloping property, it is important that the azo-type iron complex saltis still finer particle, and dispersed homogeneously.

The azo-type iron complex salts represented by the above chemicalformula [I] are as follows.

R¹—, R²—, R³— and R⁴— are same or different to each other, and onethereof is selected from the groups consisting of the hydrogen atom; thealkyl group having the straight or branch chain of 1 to 18 carbon atomssuch as methyl group, ethyl group, propyl group, isopropyl group,n-butyl group, tert-butyl group, n-pentyl group, isopentyl group, hexylgroup, heptyl group or octyl group; the alkenyl group having thestraight or branch chain of 2 to 18 carbon atoms such as vinyl group,allyl group, propenyl group or butenyl; the sulfonamide group being tohave substitutional groups; the mesyl group; the hydroxyl group; thealkoxyl group having 1 to 18 carbon atoms such as methoxyl group,ethoxyl group, propoxyl group; the acetylamino group; the benzoylaminogroup; the halogen atom such as fluorine atom, chlorine atom or bromineatom; the nitro group; the aryl group being to have substitutionalgroups such as phenyl group or naphthyl group which may have a fewsubstitutional groups such as hydroxyl group, alkyl group, aryl group orhalogen atom for example fluorine atom, chlorine atom, bromine atom.

R⁵— is selected from the groups consisting of the hydrogen atom; thealkyl group having the straight or branch chain of 1 to 18 carbon atomssuch as methyl group, ethyl group, propyl group, isopropyl group,n-butyl group, tert-butyl group, n-pentyl group, isopentyl group, hexylgroup, heptyl group or octyl group; the hydroxyl group and the alkoxylgroup of 1 to 18 carbon atoms such as methoxyl group, ethoxyl group,propoxyl group.

R⁶— is selected from the groups consisting of the hydrogen atom; thealkyl group having the straight or branch chain of 1 to 18 carbon atomssuch as methyl group, ethyl group, propyl group, isopropyl group,n-butyl group, tert-butyl group, n-pentyl group, isopentyl group, hexylgroup, heptyl group or octyl group; the hydroxyl group; the carboxylgroup; the halogen atom; and the alkoxyl group of 1 to 18 carbon atomssuch as methoxyl group, ethoxyl group, propoxyl group.

It is preferable that the azo-type iron complex salt represented by theabove chemical formula [I] is a compound represented by the followingchemical formula [II]:

(in the chemical formula [II], n is same above)

The azo-type iron complex salt represented by the following chemicalformula [I] may be other compounds represented by the following chemicalformulae [VI]-[XIII], wherein n is same above.

(in the chemical formula [VI], t-C₄H₉— is a tertiary butyl group)

(in the chemical formula [XI], t-C₈H₁₇— is a tertiary octyl group)

Especially, the compound represented by the above-mentioned chemicalformula [II] is desirable.

When the charge control agent is magnified with the scanning electronmicroscope, it is observed that it comprises the aggregate particleshaving the above size and almost uniform platy-shape. And it is observedthat the almost uniform platy-shape of the aggregate particles has about2 to 5 microns in length and about 0.5 to 1 microns in width. Since thetoner comprising the uniform charge control agent causes homogeneouselectrification property, the electrostatic latent images are formedevenly and vividly.

According to investigation upon the average particle size of the primaryparticulate crystalline of the charge control agent and the surface areaof the primary particle, it is preferable that the specific surface areadetermined from said average particle size of the primary particulatecrystalline is at least 10 m²/g. Within this range, the charge controlproperty of the charge control agent improves, to obtain the imageshaving high resolution. It is more preferable that the specific surfacearea is at least 15 m²/g.

It is preferable that the charge control agent further comprises butanolof an amount of 0.01 to 1.00% by weight. When the charge control agentis prepared using butanol, the average particle size thereof is fine. Itis guess that the excellent toner is prepared, because the chargecontrol agent comprising small amount of butanol is difficult toaggregate and easy to disperse into the toner finely.

The charge control agent has allowable residual chloride ion wherein anamount thereof is at most 200 ppm preferably. Further the charge controlagent has allowable residual sulfate ion wherein an amount thereof is atmost 100 ppm preferably. The amounts of the ion are measured as theresidual ions of the azo-type iron complex salt. The charge controlagent having higher purity improves the electrification property more.

The method for manufacturing the charge control agent comprising theazo-type iron complex salt represented by the above chemical formula [I]of the present invention, comprises steps of:

a diazotization coupling reaction first-step for preparing the monoazocompound represented by the following chemical formula [III]

(in the chemical formula [III], R¹—, R²—, R³—, R⁴—, R⁵—, and R⁶— aresame above):

a second-step for iron-complexing with said monoazo compound:

a counter ion-exchanging third-step for preparing an azo-type ironcomplex salt represented by above-mentioned formula [I]: and

a fourth-step for filtrating and drying the azo-type iron complex salt:

at least one of said second-step for iron-complexing and said counterion-exchanging third-step carries out in mixed solvent of water and thelower alcohol having 1 to 6 carbon atoms. It is preferable that thewater is included at least 70% by weight thereof.

According to the method for manufacturing, the prepared monoazo compoundand the azo-type iron complex salt are easy to crystallize. In the eachsteps of the method, the reactants and the products are controlled tofine. Thus controlling is an influential factor to prepare the chargecontrol agent comprising aggregate particles of the azo-type ironcomplex salt and the primary particulate crystalline thereof in goodyield. In the method for manufacturing, the reaction is carried out inthe mixed aqueous solvent including the lower alcohol having 1 to 6carbon atoms, to control the particulate crystalline of the azo-typeiron complex salt fine in high yield. It is more preferable that thelower alcohol is butanol.

It is preferable that the first-step carries out preparing monoazocompound by general procedures of the diazotization coupling reaction inwater, mixed solvent of water and organic solvent, or especially mixedsolvent of water and the lower alcohol having 1 to 6 carbon atoms.

It is preferable that the second-step carries out iron-complexing withthe monoazo compound prepared in the first-step, by an iron-complexingagent such as ferric sulfate, ferric chloride or ferric nitrate, inwater, mixed solvent of water and the organic solvent, or especiallymixed solvent of water and the lower alcohol having 1 to 6 carbon atomswhich has a ratio by weight of 99.9 to 70 parts water to 0.1 to 30 partsthe lower alcohol having 1 to 6 carbon atoms. The reaction is carriedout in the aqueous mixed solvent including the lower alcohol having 1 to6 carbon atoms, to control the average particle size of the chargecontrol agent. In the second step, the mixed solvent includes the loweralcohol having 1 to 6 carbon atoms of 0.5 to 9.0% by weight, especially2.0 to 8.0% by weight. It is preferable that the lower alcohol isbutanol.

It is preferable that the third-step carries out counter ion-exchangingby an ammonium compound such as aqueous ammonia, ammonium nitrate,ammonium phosphate, ammonium chloride or ammonium sulfate.

After the second-step for iron-complexing with the monoazo compound, thethird-step for counter ion-exchanging may be carried out. Thesecond-step and the third-step may be carried out simultaneously.

On counter ion-exchanging, the whole counter ion derives Na⁺ or H⁺, andthen this counter ion may be exchanged by the ion represented by theabove-mentioned chemical formula [I], to have the desired ratio n.

The ion-exchanging procedure is carried out in at least one of aqueoussolvent and nonaqueous solvent. The aqueous solvent is inexpensive.Using the aqueous solvent, the reactants and the products are easy tocrystallize, and controlled the particle size of the crystalline thereoffine.

Any continuous steps of the first-, second-, or third-step may becarried out in the same reactor. Each step thereof may be carried out inthe separate reactors. Each step thereof may be carried out throughone-pot operation without removing the solvent.

Whenever completing the reaction of each step, intermediate products maybe filtrated out to obtain a wet cake, and then the cake may be dried toobtain a dry cake. The wet or dry cake may be used for next steps as theintermediate.

A crucial procedure in the method wherein after the first-step thereaction mixture is taken out and filtrated to obtain the intermediateproducts of the wet cake, is regulation of the desired amount of thecounter ion Na⁺ of the product of the azo-type iron complex salt. So itis necessary to determine the amount of Na⁺ of the reaction mixtureprepared by the diazotization coupling reaction using for instancesodium nitrite in the first-step, and the residual amount of Na⁺ of themonoazo compound. The amount of sodium hydroxide is regulated bysubtraction of the residual amount of Na⁺ of the monoazo compound. Inthe second-step, the sodium hydroxide is added to the mixed solvent ofwater and the lower alcohol having 1 to 6 carbon atoms dispersing themonoazo compound, and then the iron-complexing agent is added thereto.By the iron-complexing reaction, the azo-type iron complex salt havingthe desired ratio of the counter ion is prepared simply. In thisreaction, it is preferable that pH is 2 to 4.

The manufactured charge control agent has fine particle size and uniformshape. So the charge control agent is unnecessary to pulverize andclassify. The method for manufacturing the charge control agent issimply and practically.

If the amount of sodium hydroxide, the amount of the lower alcoholhaving 1 to 6 carbon atoms and pH are out of above appropriate ranges,the average particle size of the charge control agent is over 4 microns.If such charge control agent is crushed with weak force by an agitatormill, a mortar and so on, the average particle size thereof is out of 1to 4 microns. And it is necessary to pulverize under high-speed flowsuch as a jet mill.

In the method wherein the second-step is carried out after thefirst-step without taking out the reaction mixture, if the amount of thelower alcohol having 1 to 6 carbon atoms is out of above appropriateranges, the average particle size of the charge control agent is over 4microns. If such charge control agent is crushed with weak force by theagitator mill, the mortar and so on, the average particle size thereofis out of 1 to 4 microns. And it is necessary to pulverize underhigh-speed flow such as the jet mill.

The manufactured charge control agent is dried, to form aggregated lumpsof about I mm to several cm by static electricity and so on. The lumpsare crushed with a crusher such as the agitator mill or the mortar, tobe the aggregate particles having the size of 1 to 4 microns easily. Theaggregate particles, which are carried out just crushing of the weakpulverization procedure, have fine particle size and uniform shape. Theaggregate particles have high and stable quality.

It is preferable that the charge control agent is manufactured from thismethod for manufacturing to come in useful.

The charge control agent is used for including into the toner forelectrostatic image development or the powder paint.

The toner for developing the electrostatic image of the presentinvention comprises the above-mentioned charge control agent and theresin for the toner. Examples of the resin for the toner are a styleneresin, an acrylic resin, an epoxy resin, a vinyl resin and a polyesterresin. The toner may comprise colorant, a magnetic material, a fluidimprovement agent or an offset prevention agent. The toner may comprisethe resin for the toner having high acid value to use for high-speedinstruments. It is preferable that the acid value is 20 to 100 mgKOH/g.

The toner comprises, for example 100 parts by weight of the resin forthe toner, 0.1 to 10 parts by weight of the charge control agent, and0.5 to 10 parts by weight of the colorant.

The copied image using the negative electrified toner by the friction isvivid and high quality. The toner causes the faster rise speed of theelectrification thereof. So the toner develops the electrostatic latentimage clearly and forms vivid images of high resolution, not only underhigh speed copying but also under low speed copying at rotating speed ofat most 600 cm/min. The toner has the excellent copying property.

As the colorant in the toner, known various dyestuffs or pigments areused. Examples of colorant are organic pigments such as quinophtharoneyellow, isoindolinone yellow, perinone orange, perinone red, perylenemaroon, rhodamine 6G lake, quinacridone red, anthanthrone red, rosebengale, copper phthalocyanine blue, copper phthalocyanine green anddiketopyrrolopyrrole; inorganic pigments such as carbon black, titaniumwhite, titanium yellow, ultramarine, cobalt blue, red iron oxide,aluminum powder, bronze; metal powder. And examples of colorant aredyestuffs or pigments treated with higher fatty acids, synthetic resins.The exemplified colorant may be used solely or plurally with mixing.

For improving the quality of the toner, the additive agents may be addedto the toner internally or externally. Examples of the additive agentsare the offset prevention agent; the fluid improvement agent such asmagnesium fluoride and various metal oxides for example silica, aluminumoxide, titanium oxide; a cleaning auxiliary such as a metallic soap forexample stearic acid, particulates of various synthetic resin forexample fluorine-contained resin particulates, silicone synthetic resinparticulates, stylene-(meth)acrylic synthetic resin particulates, and soon.

After the toner is mixed with carrier powder, it is used for developingby a two-component magnetic brush development method and so on. Thecarrier powder can be used all known carrier powder, and is not limitedespecially. Examples of the carrier powder are the powder of iron ornickel or ferrite whose particle size is ranging from 50 to 200 micronsgenerally, glass beads, the modified powder or beads whose surfaces arecoated with an acrylate copolymer, a styrene-acrylate copolymer, astyrene-acrylate copolymer, a silicone resin, a polyamide resin or afluoroethylene-contained resin, and so on.

The toner is used for the mono-component development method. On theoccasion of the above-mentioned preparing of the toner, the toner isprepared with adding and dispersing ferromagnetic particulates such asthe powder of iron or nickel or ferrite and so on. Examples of thedevelopment methods are a contact development method and a jumpingdevelopment method.

Example of the method for manufacturing the toner is so-calledpulverization method. This method is specifically as follows. The resin,a mold lubricant consisting of a material having low softening point,the colorant, the charge control agent and so on are dispersedhomogeneously by a pressurized kneader, a extruder or a media dispersingmachine. It is pulverized mechanically, or pulverized by collision withtargets under jet flow, to prepare the pulverized toner having thedesired particle size. Particle size distribution thereof is narrowedthrough the classification process, to prepare the desired toner.

Moreover, the method of manufacturing the polymerized toner is asfollows, for example. The mold lubricant, the colorant, the chargecontrol agent, a polymerization initiator and the other additive agentsare added to a monomer. It is dissolved or dispersed homogeneously by ahomomixer, an ultrasonic disperser and so on, to prepare a monomercomposition. The monomer composition is dispersed in water phaseincluding a dispersion stabilizer by the homomixer and so on. Whendroplets consisting of the monomer composition are attained to thedesired particle size of the toner, granulation is stopped. It is keptthe condition of the same particle size by the effect of the dispersionstabilizer, or gently stirred to prevent from sedimentation thereof. Thepolymerization reaction is carried out at 40 degrees centigrade atleast, preferable at 50 to 90 degrees centigrade. In the latter of thepolymerization reaction, it may be risen the temperature. In the latterof the polymerization reaction, or after the polymerization reaction, apart of the aqueous solvent may be distilled in order to remove togetherthe unreacted monomer, byproducts and so on. In thus suspensionpolymerization method, it is preferable that 300 to 3000 parts by weightof water as the solvent for the dispersion are used to 100 parts byweight of the monomer composition.

After the polymerization reaction, the prepared toner particles arewashed, filtrated out and dried, to obtain the polymerized toner.

An image formation process of electrophotography of the presentinvention comprises a step for developing the electrostatic latent imageon the electrostatic latent image frame by a developer including thetoner.

It is preferable that the image formation process of electrophotographymay comprise steps of:

-   a step for absorbing developer that includes the toner for forming a    layer thereof on developer-carrier frame which rotates at most 900    cm/min., that is for example arranged to an electrostatic latent    image frame with an interstice:-   the step for developing the electrostatic latent image by absorbing    the toner in the layer on the electrostatic latent image frame.

As it is mentioned above in detail, the charge control agent of thepresent invention is fine and uniform shape, and unnecessary topulverize using the jet mill and so on. It is manufactured simply. Thecharge control agent performs to quicken the rise speed of theelectrification and electrify sufficiently. So the charge control agentis used for the toner for electrostatic image development withwidespread purposes of the high or low speed copy. Further the chargecontrol agent is used for the powder paint of the electrostatic powderpainting. The charge control agent does not include toxic heavy metals,to have high safety, so that does not cause environmental pollution.

The toner for electrostatic image development comprising the chargecontrol agent performs to quicken the rise speed of the electrification.The toner causes electrifying sufficient quantity of the negative chargeand keeping stable electrification for a long period, because the chargecontrol agent is dispersed homogeneously in the toner. The toner is usedfor the development of the electrostatic latent image under electrophotography system. The images, that is formed by transferring theelectrostatic latent image onto printing paper, have stability,vividness, high resolution and clearness without foggy.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a graph shown a correlation between rotation time and quantityof the frictional electrification using the toner for the electrostaticimage development that applies this invention, under each rotationspeed.

FIG. 2 is a graph shown a correlation between rotation time and quantityof the frictional electrification using another toner for theelectrostatic image development that applies this invention, under eachrotation speed.

DETAILED EXPLANATION OF THE INVENTION

Hereunder, embodiments of the charge control agent of this invention andthe toner for developing the electrostatic image comprising thereof areexplained in detail.

EXAMPLE 1

The method for manufacturing the charge control agent comprising theazo-type iron complex salt represented by the above chemical formula[II] is explained, referring to the following chemical reactionequations which is an example of synthesizing the complex salt.

58.1 g of 2-amino-4-chlorophenol (chemical formula [XIV]) as a startingmaterial and 120.0 g of concentrated hydrochloric acid were added to680.3 g of water. For diazotization, 36.3 g of 36% sodium nitriteaqueous solution was added thereto gradually with cooling a reactionvessel by ice, to obtain the diazonium salt. The diazonium salt solutionwas added dropwise in a short time to aqueous solution of 17.4 g ofNaphthol AS (chemical formula [XV]), 280 g of 20.5% sodium hydroxideaqueous solution and 800 mL of water, and then it was reacted for 2hours. The precipitated monoazo compound (chemical formula [XVI]) wasfiltrated out and washed with water, to obtain 688.4 g of the wet cakehaving 78.4% of water content.

When a small part of the wet cake of the monoazo compound (chemicalformula [XVI]) was dried and determined the amount of sodium by atomicabsorption spectro photometry, the amount of sodium was 2.88%.

285.4 g of the wet cake of the monoazo compound (chemical formula [XVI])was dispersed in the mixed solvent of 94.3 g of normal butanol and 1180g of water. 25.0 g of 20.5% sodium hydroxide aqueous solution, that isregulating the amount of residual sodium thereof to converted solidweight of the wet cake, was added to the mixed solvent. It was heated at80 degrees centigrade, and stirred to disperse for 30 minutes. Then 36.0g of 41% ferric sulfate aqueous solution was added dropwise. It washeated at 96 degrees centigrade, and refluxed for 2 hours, to preparethe azo-type iron complex salt including hydrogen ion (chemical formula[XVII]). Further it was refluxed, 126.9 g of the water and normalbutanol were removed using Dean-Stark traps. After cooling until roomtemperature, 19.4 g of ammonium sulfate and 20.0 g of 25% aqueousammonia were added. Then it was refluxed for 2 hours at 96 degreescentigrade, to exchange the counter ion. After the reaction, it wascooled. The precipitated azo-type iron complex salt (chemical formula[II]) was filtrated out and washed with water, to obtain 57.3 g of thedesired charge control agent.

It was dried, to form aggregated lumps of 1 mm to several cm. The lumpswere crushed with the agitator mill or mashed with the mortar, to bepowdery.

The charge control agent was analyzed chemically and evaluatedphysically.

(The Observation by the Scanning Electron Microscope)

The charge control agent was observed the particle size and the shapeusing the scanning electron microscope S2350 that is available fromHitachi, Ltd. When the charge control agent was magnified, it wasobserved that the size of the primary particulate was 1 to 4 microns andthe shape was almost uniform platy-shape.

(The Measurement of the Average Particle Size of the Aggregate Particlesof the Charge Control Agent)

20 mg of the charge control agent was added to solution of 20 mL ofwater and 2 mL of an activator: scourol 100 that is available from KaoCorporation, to prepare mixture. About 1 mL of the mixture was add to120 mL of dispersed water in particle size distribution measurementequipment LA-910 that is available from Horiba, Ltd. After it wasirradiated with the ultrasonic wave for 1 minute, the particle sizedistribution was measured. The average particle size of the aggregateparticles of the charge control agent was 2.2 microns.

(The Average Particle Size of the Primary Particulate Crystalline, Whichthe Charge Control Agent was Dispersed Finely)

20 mg of the aggregate particles of the charge control agent was addedto solution of 20 mL of water and 2 mL of the activator: scourol 100that is available from Kao Corporation, to prepare mixture. The mixturewas irradiated with the ultrasonic wave for 10 minutes. 1 or 2 dropletsof the mixture were added to 120 mL of dispersed water in the particlesize distribution measurement equipment LA-910 that is available fromHoriba, Ltd. After it was irradiated with the ultrasonic wave forfurther 1 minute, to disperse the aggregate particles finely until to bethe primary particulate crystalline, the particle size distribution wasmeasured. When the result with the measured particle size distributiondiffers from the result with the observed particle size by the scanningelectron microscope awfully, it was irradiated with the ultrasonic wavefor further 5 minutes to disperse the aggregate particles more finelyuntil to be the primary particulate crystalline and measured theparticle size distribution again. The average particle size of theprimary particulate crystalline of the charge control agent was 1.6microns.

(The Measurement of the Specific Surface Area of the Charge ControlAgent)

The specific surface area of the charge control agent, that is B.E.T.,was measured using specific surface area measurement equipment NOVA-1200that is available from QUANTACHROME Corporation. After an emptylarge-cell having 9 mm of the length was weighed, about 0.2 g of thecharge control agent was put in to ⅘ of the cell. The cell was set in adrying chamber and heated at 120 degrees centigrade for 1 hour, todegas. The cell was cooled and weighed, to calculate the weight of thecharge control agent. The cell was set on the analysis station, tomeasure. The specific surface area of the primary particulatecrystalline determined from the average particle size was 15.3 m²/g.

(The Measurement of the Amount of Ammonium Ion and the Amount of SodiumIon)

The including amount of sodium of the charge control agent et ceterawere measured using atomic absorption spectro photometer AA-660 that isavailable from Shimadzu Corporation, and elementary analyzer 2400 IICHNS/O that is available from Perkin Elmer Instruments. As the ratio ofthe counter ions, the ammonium ion was 97.2 mol % and sodium ion was 2.8mol %.

(Measurement of the Amount of Residual Chloride Ion and the Amount ofResidual Sulfate Ion)

The amount of residual chloride ion and the amount of residual sulfateion of the charge control agent were measured using ion exchangechromatograph DX-300 that is available from DIONEX Corporation. Theamount of residual chloride ion was 112 ppm. The amount of residualsulfate ion was below a limit of the detection that was 100 ppm.

(Measurement of the Amount of the Organic Solvent)

The amount of the organic solvent of the charge control agent wasmeasured using gas chromatograph SERIES II 5890 that is available fromHEWLETT-PACKARD Company. The amount of normal butanol was 0.22% byweight.

These results are shown in Table 1.

EXAMPLE 2

As another lot of the monoazo compound (chemical formula [XVI]) with thesame procedure as Example 1, wherein the obtained amount differs, wasprepared. The precipitated monoazo compound was filtrated out and washedwith water, to obtain 1620.4 g of the wet cake having 73.8% of watercontent.

When a small part of the monoazo compound (chemical formula [XVI]) wasdried and determined the amount of sodium by atomic absorption spectrophotometry, the amount of sodium was 1.90%.

160 g of the wet cake of the monoazo compound (chemical formula [XVI])was dispersed in the mixed solvent of 22.2 g of normal butanol and283.39 g of water. 22.05 g of 20.5% sodium hydroxide aqueous solution,that is regulating the amount of residual sodium thereof to convertedsolid weight of the wet cake, was added to the mixed solvent. It washeated at 80 degrees centigrade, and stirred to disperse for 30 minutes.Then 24.5 g of 41% ferric sulfate aqueous solution was added dropwise.It was heated at 93 degrees centigrade, and refluxed for 2 hours, toprepare the azo-type iron complex salt including hydrogen ion (chemicalformula [XVII]). Further it was refluxed, 34.3 g of the water and normalbutanol were removed using Dean-Stark traps. After cooling until roomtemperature, 3.32 g of ammonium sulfate and 13.65 g of 25% aqueousammonia were added. Then it was refluxed for 2 hours at 96 degreescentigrade, to exchange the counter ion. After the reaction, it wascooled. The precipitated azo-type iron complex salt (chemical formula[II]) was filtrated out and washed with water, to obtain 38.7 g of thedesired charge control agent.

It was dried, to form aggregated lumps of 1 mm to several cm. The lumpswere crushed with the agitator mill or mashed with the mortar, to bepowdery.

The charge control agent was analyzed chemically and evaluatedphysically as the same as Example 1. When the charge control agent wasobserved using the scanning electron microscope, it was observed thatthe size of the primary particulate was within the range of 1 to 4microns and the shape was almost uniform platy-shape. The averageparticle size of the aggregate particles of the charge control agent was3.5 microns. The average particle size of the primary particulatecrystalline, that the charge control agent was dispersed finely, was 1.8microns. These results of the charge control agent of Example 2, that isanalyzed chemically and evaluated physically, are shown in Table 1together.

EXAMPLE 3

As another lot of the monoazo compound (chemical formula [XVI]) with thesame procedure as Example 1, wherein the water content differs, wasprepared. The precipitated monoazo compound was filtrated out and washedwith water, to obtain the wet cake that had 68.45% of water content andwas 99.00% of purity measured by liquid chromatography. When a smallpart of the wet cake of the monoazo compound was dried and determinedthe amount of sodium by atomic absorption spectro photometry, the amountof sodium was 4.26%.

70.0 g of the wet cake of the monoazo compound was dispersed in themixed solvent of 11.53 g of 1-pentanol and 424.27 g of water. 7.1 g of20.5% sodium hydroxide aqueous solution, that is regulating the amountof residual sodium thereof to converted solid weight of the wet cake,was added to the mixed solvent. It was heated at 80 degrees centigrade,and stirred to disperse for 30 minutes. Then 12.76 g of 41% ferricsulfate aqueous solution was added dropwise. At this point, pH of thereaction mixture was 2.7. It was heated at 97 degrees centigrade, andrefluxed for 3 hours, to prepare the azo-type iron complex salt. Theprecipitated azo-type iron complex salt was filtrated out and washedwith water, to obtain 53.4 g of the wet cake having 60.3% of watercontent.

The wet cake was dispersed in 151 g of water. 1.5 g of ammonium sulfate,6.1 g of 25% aqueous ammonia and 5.5 g of normal butanol were addedthereto. It was heated at 97 degrees centigrade and refluxed for 2 hoursto exchange the counter ion. The precipitated azo-type iron complex saltwas filtrated out, washed with water and dried, to obtain 19.5 g of thedesired charge control agent.

The charge control agent was analyzed chemically and evaluatedphysically as the same as Example 1. The average particle size of theaggregate particles of the charge control agent was 4.0 microns. Theaverage particle size of the primary particulate crystalline, that thecharge control agent was dispersed finely, was 2.1 microns. Theseresults of the charge control agent of Example 3, that is analyzedchemically and evaluated physically, are shown in Table 1 together.

EXAMPLE 4

The monoazo compound salt represented by the following chemical formula[XVIII] was prepared as the same as Example 1, except for using2-amino-4-sulfonamido derivative instead of 2-amino-4-chlorophenol(chemical formula [XIV]).

The precipitated monoazo compound was filtrated out and washed withwater, to obtain the wet cake that had 58.3% of water content and was97.04% of purity measured by liquid chromatography. When a small part ofthe wet cake of the monoazo compound was dried and determined the amountof sodium by atomic absorption spectro photometry, the amount of sodiumwas 4.20%.

57.00 g of the wet cake of the monoazo compound, that is 0.050 mol, wasdispersed in the mixed solvent of 24.24 g of normal butanol and 409.02 gof water. 9.37 g of 20.5% sodium hydroxide aqueous solution, that is0.048 mol and is regulating the amount of residual sodium thereof toconverted solid weight of the wet cake, was added to the mixed solvent.It was heated at 80 degrees centigrade, and stirred to disperse for 30minutes. Then 12.24 g of 41% ferric sulfate aqueous solution, that was0.013 mol, was added dropwise. At this point, pH of the reaction mixturewas 3.83. It was heated at 97 degrees centigrade, and refluxed for 3hours, to prepare the azo-type iron complex salt. The precipitatedazo-type iron complex salt was filtrated out and washed with water, toobtain 50.05 g of the wet cake having 56.3% of water content.

The wet cake was dispersed in 161 g of water. 1.6 g of ammonium sulfate,6.3 g of 25% aqueous ammonia and 5.7 g of butanol were added thereto. Itwas heated at 97 degrees centigrade and refluxed for 2 hours to exchangethe counter ion. The precipitated azo-type iron complex salt (chemicalformula [VII]) was filtrated out, washed with water and dried, to obtain21.1 g of the desired charge control agent.

The charge control agent was analyzed chemically and evaluatedphysically as the same as Example 1. When the charge control agent wasobserved using the scanning electron microscope, it was observed thatthe size of the primary particulate was within the range of 1 to 4microns and the shape was almost uniform platy-shape. The averageparticle size of the aggregate particles of the charge control agent was3.9 microns. The average particle size of the primary particulatecrystalline, that the charge control agent was dispersed finely, was 1.7microns. These results of the charge control agent of Example 4, that isanalyzed chemically and evaluated physically, are shown in Table 1together.

EXAMPLE 5

16.2 g of 2-amino-4-chlorophenol (chemical formula [XIV]) as a startingmaterial and 26.1 g of concentrated hydrochloric acid were added to124.0 g of water. For diazotization, 21.7 g of 36% sodium nitriteaqueous solution was added thereto gradually with cooling the reactionvessel by ice, to obtain the diazonium salt. The diazonium salt solutionwas added dropwise in a short time to aqueous solution of 25.0 g ofNaphthol AS (chemical formula [XV]), 55.9 g of 20.5% sodium hydroxideaqueous solution and 186 mL of water, then it was reacted for 2 hours,to obtain the reaction mixture including the precipitated monoazocompound (chemical formula [XVI]). 12.0 g of butanol, 18.2 g of 20.5%sodium hydroxide aqueous solution and 22.7 g of 41% ferric sulfateaqueous solution were added to the reaction mixture. It was heated at 97degrees centigrade, and refluxed for 2 hours, to prepare the azo-typeiron complex salt (chemical formula [XVII]). The precipitated azo-typeiron complex salt (chemical formula [XVII]) was filtrated out and washedwith water, to obtain 86.63 g of wet cake having 55.1% of water content.

The wet cake was dispersed in 282 g of water. 3.00 g of ammoniumsulfate, 11.0 g of 25% aqueous ammonia and 9.9 g of butanol were addedthereto. It was heated at 97 degrees centigrade and refluxed for 2 hoursto exchange the counter ion. The precipitated azo-type iron complex salt(chemical formula [II]) was filtrated out, washed with water and dried,to obtain 34.9 g of the desired charge control agent.

The charge control agent was analyzed chemically and evaluatedphysically as the same as Example 1. The average particle size of theaggregate particles of the charge control agent was 3.9 microns. Theaverage particle size of the primary particulate crystalline, that thecharge control agent was dispersed finely, was 2.0 microns. Theseresults of the charge control agent of Example 5, that is analyzedchemically and evaluated physically, are shown in Table 1 together.

COMPARATIVE EXAMPLE 1

The wet cake of the monoazo compound salt (chemical formula [XVI]), thatis the intermediate, was prepared as the same as Example 1.

285.4 g of the wet cake of the monoazo compound (chemical formula [XVI])was dispersed in 1180 g of water. 25.0 g of 20.5% sodium hydroxideaqueous solution, that is regulating the amount of residual sodiumthereof to converted solid weight of the wet cake, was added to themixed solvent. It was heated at 80 degrees centigrade, and stirred todisperse for 30 minutes. Then 36.0 g of 41% ferric sulfate aqueoussolution was added dropwise. It was heated at 85 degrees centigrade, andrefluxed for 2 hours, to prepare the azo-type iron complex salt(chemical formula [XVII]). The yield of the azo-type iron complex saltwas 19.3%. When the azo-type iron complex salt was magnified, it wasobserved that crystal form was ununiform and lumps.

The charge control agent was analyzed chemically and evaluatedphysically as the same as Example 1. The average particle size of theaggregate particles was 22.4 microns. When it was observed using thescanning electron microscope, it was observed that the particle size was4 microns at most. These results of the charge control agent ofComparative Example 1, that is analyzed chemically and evaluatedphysically, are shown in Table 1 together. TABLE 1 comparativeEvaluation Criteria Example 1 Example 2 Example 3 Example 4 Example 5Example 1 Average Aggregate 2.2 3.5 4.0 3.9 3.9 22.4 Particle ParticleSize Primary 1.6 1.8 2.1 1.7 2.0 14.8 (micron) Particle Mol Ratio Na⁺2.8 7.5 15.8 26.8 21.7 100 of NH₄ ⁺ 97.2 92.5 84.2 73.2 78.3 0 CounterIon (mol %) Amount of (ppm) 112 Below 147 Below Below 115 Residual Limitof Limit of Limit of Chloride Detection Detection Detection Ion Amountof (ppm) Below Below Below Below Below 2070 Residual Limit of Limit ofLimit of Limit of Limit of Sulfate Detection Detection DetectionDetection Detection Ion

Hereunder, examples of preparing the toner for developing theelectrostatic image using the charge control agent are explained.

EXAMPLE 6

1 weight part of the charge control agent prepared in Example 1,

100 weight parts of stylene-acrylic copolymer CPR-600B that is availablefrom Mitsui Chemicals, Inc.,

6 weight parts of carbon black MA-100 that is available from MitsubishiChemical Corporation, and

2 weight parts of low-grade polypropylene VISCOL 550P that is availablefrom Sanyo Kasei Industries, Ltd. were mixed beforehand, to prepare apre-mix. The pre-mix was melted and kneaded. After cooling, it waspulverized coarsely by an ultra-centrifugal pulverizing machine. Theobtained coarse pulverulent was fined using an air jet mill attached aclassifier, to obtain the black toner having 5 to 15 microns of particlesize.

5 weight parts of the toner and 95 weight parts of iron powder carrierTEFV200/300 that is available from Powder Tech Corporation were loadedin three drums respectively. The developing rollers confronted thereofwere rotated at rotation speed of (A) 1200 cm/minuets, (B) 900cm/minuets, and (C) 600 cm/minuets. The quantity of the frictionalelectrification of the toner with passage of time was determined byblow-off method using an instrument TB-200, that the blow-off measuringinstrument of the quantity of the electrification is available fromToshiba Chemical Corporation. The results are shown in (A) to (C) ofFIG. 1.

EXAMPLE 7

The black toner was prepared as the same as Example 6, except for usingthe charge control agent of Example 4 instead of the charge controlagent of Example 1. The quantity of the frictional electrification wasdetermined by blow-off method. The result are shown in (A) to (C) ofFIG. 2.

EXAMPLE 8

After 450 weight parts of 0.1 mol/L Na₃PO₄ aqueous solution was added to710 weight parts of deionized water, it was heated at 60 degreescentigrade. Stirring by 5000 rpm using T.K. HOMO MIXER that is availablefrom Tokushu Kika Kogyo Co., Ltd., 68 weight parts of 1.0 mol/L CaCl₂aqueous solution was added gradually, to prepare water dispersedCa(PO₄)₂.

The other hand, 170 weight parts of styrene monomer, 25 weight parts ofcarbon, 4 weight parts of the dispersed solution, and 9 weight parts ofthe azo-type iron complex salt (chemical formula [II]) of Example 1 wereadded to DYNO-MILL ECM-PIROT that is available from Shinmaru EnterprisesCorporation. It was stirred to disperse with 0.8 mm of zirconia beadsusing a stirring blade at 10 m/sec. of peripheral speed for 3 hours, toobtain the dispersed solution. 10 weight parts of2,2-azobis(2,4-dimethylvaleronitrile) was added to the dispersedsolution at 60 degrees centigrade, to prepare the monomer composition.

The monomer composition was added to the water dispersed Ca(PO₄)₂. Itwas stirred at 10000 rpm for 15 minuets, to granulate. Then it wasstirred using the stirring blade at 80 degrees centigrade for 10 hours,to polymerize. After the reaction, the unreacted monomer was removedunder reduced pressure. After cooling, hydrochloric acid was added todissolved Ca(PO₄)₂. It was filtrated, washed with water, and dried, toobtain the black toner.

5 weight parts of the black toner and 95 weight parts of ferrite carrierwere mixed, to obtain the developer. Under the environment of thetemperature of 26 to 29 degrees centigrade and the humidity of 55 to 63%, the images were formed using the developer. According to endurancetest that is formed images onto 5000 pieces of paper, the initial andfinal of the images had the same density, high quality, and, no printingexcept inside.

COMPARATIVE EXAMPLE 2

The toner of Comparative Example was prepared as the same as Example 6except for using the charge control agent of Comparative Example 1. Thequantity of the frictional electrification of the toner was determinedas the same. The result are shown in (A) to (C) of FIG. 1 and FIG. 2.

It was evidence with FIG. 1 and FIG. 2 that the toner of Examples hadthe fast rise speed of the electrification and the sufficient quantityof the electrification, not only under high rotating speed but alsounder low rotating speed.

1. A charge control agent comprising aggregate particles of an azo-typeiron complex salt represented by the following chemical formula [I]:

in the chemical formula [I], R¹⁻, R²⁻, R³⁻, and R⁴⁻ are same ordifferent to each other, and one thereof is selected from the groupsconsisting of a hydrogen atom, an alkyl group having a straight orbranch chain of 1 to 18 carbon atoms, an alkenyl group having a straightto branch chain of 2 to 18 carbon atoms, a sulfonamide group being tohave substitutional groups, a mesyl group, a hydroxyl group, an alkoxylgroup of 1 to 18 carbon atoms, an acytlamino group, a benzoylaminogroup, a halogen atom, a nitro group and an aryl group being to havesubstitutional groups; R⁵⁻ is a hydrogen atom, an alkyl group having astraight or branch chain fo 1 to 18 carbon atoms, a hydroxyl group or analkoxyl group of 1 to 18 carbon atoms; R⁶⁻ is a hydrogen atom, an alkylgroup having a straight or branch chain of 1 to 18 carbon atoms, ahydroxyl, group, a carboxyl group, a halogen atom, or an alkoxyl groupof 1 to 18 carbon atoms; n is 0.7 to 0.99, said aggregate particles havean average size of 1 to 4 microns and an average particle size of aprimary particulate crystalline that is fined the aggregate particleswith ultrasonic irradiation, is at most 3 microns.
 2. The charge controlagent according to claim 1, wherein a primary particle of said azo-typeiron complex salt has a size of at most 4 microns.
 3. The charge controlagent according to claim 1, wherein said azo-type iron complex salt isrepresented by the following chemical formula [II]

in the chemical formula [II], n is the same above.
 4. The charge controlagent according to claim 1, wherein said aggregate particles of theazo-type iron complex salt are almost uniform platy-shape.
 5. The chargecontrol agent according to claim 1, wherein a specific surface areadetermined from said average particle size of the primary particulatecrystalline is at least 10 m²/g
 6. The charge control agent according toclaim 1, wherein allowable residual sulfate ion is at most 100 ppm, andallowable residual chloride ion is at most 200 ppm.
 7. The chargecontrol agent according to claim 1, further comprising butanol of anamount of 0.01 to 1.00% by weight.
 8. A method for manufacturing acharge control agent comprising steps of: a diazotization couplingreaction step for preparing monoazo comound represented by the followingchemical formula [III]

(in the chemical formula [III], R¹⁻, R²⁻, R³⁻, and R⁴⁻ are same ordifferent to each other, and one thereof is selected from the groupsconsisting of a hydrogen atom, an alkyl group having a straight orbranch chain of 1 to 18 carbon atoms, an alkenyl group having a straightor branch chain of 2 to 18 carbon atoms, a sulfonamide group being tohave substitutional, a mesyl group, a hydroxyl group, an alkoxyl groupof 1 to 18 carbon atoms, an acytlamino group, a benzoylamino group, ahalogen atom, a nitro group and an aryl group being to havesubstitutional groups; R⁵⁻ is a hydrogen atom, an alkyl group having astraight or branch chain of 1 to 18 carbon atoms, a hydroxyl group or analkoxyl group of 1 to 18 carbon atoms; R⁶⁻ is a hydrogen atom, an alkylgroup having a straight or branch chain of 1 to 18 carbon atoms, ahydroxyl group, a carboxyl group, a halogen atom or an alkoxyl group of1 to 18 carbon atoms): a step for iron-complexing with said monoazocompound: a counter ion-exchanging step for preparing an azo-type ironcomplex salt represented by the following chemical formula [I]

(in the chemical formula [I], R¹⁻, R²⁻, R³⁻, and R⁴⁻ are same ordifferent to each other, and one thereof is selected from the groupsconsisting of a hydrogen atom, an alkyl group having a straight orbranch chain of 1 to 18 carbon atoms, an alkenyl group having a straightto branch chain of 2 to 18 carbon atoms, a sulfonamide group being tohave substitutional groups, a mesyl group, a hydroxyl group, an alkoxylgroup of 1 to 18 carbon atoms, an acytlamino group, a benzoylaminogroup, a halogen atom, a nitro group and an aryl group being to havesubstitutional groups; R⁵⁻ is a hydrogen atom, an alkyl group having astraight or branch chain fo 1 to 18 carbon atoms, a hydroxyl group or analkoxyl group of 1 to 18 carbon atoms; R⁶⁻ is a hydrogen atom, an alkylgroup having a straight or branch chain of 1 to 18 carbon atoms, ahydroxyl, group, a carboxyl group, a halogen atom, or an alkoxyl groupof 1 to 18 carbon atoms; n is 0.7 to 0.99), and a step for filtratingand drying the azo-type iron complex salt: at least one of said step forthe iron-complexing and said counter ion-exchanging step is carried outin mixed solvent of a lower alcohol having 1 to 6 carbon atoms and waterincluded at least 70% by weight thereof, and said charge control agentcomprises aggregate particles of said azo-type iron complex salt thatsaid aggregate particles have an average particle size of 1 to 4 micronsand an average particle size of a primary particulate crystalline, thatis fined the aggregate particles with ultrasonic irradiation, is at most3 microns.
 9. The method according to claim 7, wherein said mixedsolvent includes the lower alcohol of 0.5 to 9.0% by weight.
 10. Themethod according to claim 8, wherein said lower alcohol is butanol. 11.A charge control agent manufactured from a method comprising steps: adiazotization coupling reaction step for preparing monoazo compoundrepresented by the following chemical formula [III]

(in the chemical formula [III], R¹⁻, R²⁻, R³⁻, and R⁴⁻ are same ordifferent to each other, and one thereof is selected from the groupsconsisting of a hydrogen atom, an alkyl group having a straight orbranch chain of 1 to 18 carbon atoms, an alkenyl group having a straightor branch chain of 2 to 18 carbon atoms, a sulfonamide group being tohave substitutional, a mesyl group, a hydroxyl group, an alkoxyl groupof 1 to 18 carbon atoms, an acytlamino group, a benzoylamino group, ahalogen atom, a nitro group and an aryl group being to havesubstitutional groups; R⁵⁻ is a hydrogen atom, an alkyl group having astraight or branch chain of 1 to 18 carbon atoms, a hydroxyl group or analkoxyl group of 1 to 18 carbon atoms; R⁶⁻ is a hydrogen atom, an alkylgroup having a straight or branch chain of 1 to 18 carbon atoms, ahydroxyl group, a carboxyl group, a halogen atom or an alkoxyl group of1 to 18 carbon atoms): a step for iron-complexing with said monoazocompound: a counter ion-exchanging step for preparing an azo-type ironcomplex salt represented by the following chemical formula [I]

(in the chemical formula [I], R¹⁻, R²⁻, R³⁻, R⁴⁻, R⁵⁻ and R⁶⁻ are thesame above, n is 0.7 to 0.99): and a step for filtrating and drying heazo-type iron complex salt: at least one of said step for theion-complexing and said counter ion-exchanging step is carried out inmixed solvent of a lower alcohol having 1 to 6 carbon atoms and waterincluded at least 70% by weight thereof, and said charge control agentcomprises aggregate particles of said azo-type iron complex salt thatsaid aggregate particles have an average particle size of 1 to 4 micronsand an average particle size of a primary particulate crystalline, thatis fined the aggregate particles with ultrasonic irradiation, is at most3 microns.
 12. The charge control agent to claim 11, wherein said mixedsolvent includes the lower alcohol of 0.5 to 9.0% by weight. 13.-23.(canceled)